The examination of goods which are packed in containers, for example, fruit juices in drink bottles, by means of X-rays is a process known in the food industry. Problems arise when checking for foreign bodies that have a higher density than the packed goods and, therefore, fall to the bottom of the containers. In the case of containers with a dished bottom, as is the case with many drink bottles, the foreign bodies slide on the bulge of the container bottom to the inner container edge. There, they are hard to recognize by means of X-rays, as the X-rays must penetrate not only the vertical container wall but also the bottom of the container. During this process the bottles are oriented, because of the bulge of the container bottom, at an angle of, for example, 10° to the dished surface of the container bottom and therefore travel a very long distance inside the container material. An additional attenuation of the X-rays by any foreign bodies present therefore has only relatively little effect and is frequently no longer detectable. Also, unevennesses in the surface of the container bottom can easily be mistaken for a foreign body.
EP-A-0 795 746 discloses examining the containers using two X-rays, one of which points 45° in the direction of transport and the other of which points 45° against the direction of transport, with the result that they are at right angles to each other.
EP-A-0 961 114 discloses turning the containers upside down for this examination so that any foreign bodies present drop down to the top of the container near the closure where they can be recognized with certainty by means of X-rays.
WO 01/44791 discloses tilting the containers sideways by roughly 80° and then examining them for foreign bodies using a vertically directed X-ray.